The present invention relates to a surface property-improving agent which can enhance the appearance and abrasion resistance of a molded body made of a polyolefin resin, which can suppress the bleeding of the molded body, and which can maintain the performance thereof even though being exposed to severe environments; a resin composition containing the same; and a resin-molded body made thereof.
Soft vinyl chloride resins, which have hitherto occupied the mainstream of materials for automotive interior parts such as automotive instrument panels and door trims, have recently been being replaced with polyolefin resins such as polypropylene, polyethylene, thermoplastic polyolefin elastomers because of advantages such as light weight, easiness in recycling, high cost performance, and no gas emission during combustion. However, there is a disadvantage in that automotive interior parts made of the polyolefin resins are inferior in abrasion resistance, wear resistance, and emboss retention to conventional automotive interior parts made of vinyl chloride resins.
Japanese Unexamined Patent Application Publication No. 2009-167352, which has been filed by the applicant, discloses a surface property-improving agent for compensating for this disadvantage. The surface property-improving agent disclosed in Japanese Unexamined Patent Application Publication No. 2009-167352 contains a non-polar wax with a melting point of 50° C. to 100° C. and a polymer produced by subjecting a mixed solution containing a vinyl monomer and a radical polymerization initiator to emulsion polymerization or suspension polymerization. The addition of the surface property-improving agent to a polyolefin resin suppresses the bleeding of a resin-molded body made of the polyolefin resin, odor, and fogging and enhances the appearance and abrasion resistance of the resin-molded body. Examples of the vinyl monomer include alkyl(meth)acrylates having an alkyl chain with one to 20 carbon atoms, vinyl monomers with an acid group, vinyl monomers with a hydroxyl group, vinyl monomers with an epoxy group, vinyl monomers with a cyano group, and the like.
The surface property-improving agent described in Japanese Unexamined Patent Application Publication No. 2009-167352 can maintain good surface properties in ordinary environments. However, it has become clear that there is a problem in that in the case of using the surface property-improving agent described in Japanese Unexamined Patent Application Publication No. 2009-167352, the abrasion resistance of a resin-molded body is significantly reduced by exposing the resin-molded body to a high-temperature environment for a long time.
Accordingly, there has been a need for an improved surface property-improving agent.